Cuar. XV.] DROSERACE®. 287 
ammonia brought to them by the rain. It is moreover 
probable that the glands of some of the above-named plants 
obtain animal matter from the insects which are occasionally 
entangled by the viscid secretion. 
ConcLuDING REMARKS ON THE DROSERACEÆ. 
The six known genera composing this family have now 
been described in relation to our present subject, as far as 
my means have permitted. They all capture insects. This 
is effected by Drosophyllum, Roridula, and Byblis, solely by 
the viscid fluid secreted from their glands; by Drosera, 
through the same means, together with the movements of 
the tentacles; by Dionæa and Aldrovanda, through the 
closing of the blades of the leaf. In these two last genera 
rapid movement makes up for the loss of viscid secretion. 
In every case it is some part of the leaf which moves. In 
Aldrovanda it appears to be the basal parts alone which 
contract and carry with them the broad, thin margins of the 
lobes. In Dionza the whole lobe, with the exception of the 
marginal prolongations or spikes, curves inwards, though 
the chief seat of movement is near the midrib. In Drosera 
the chief seat is in the lower part of the tentacles, which, 
homologically, may be considered as prolongations of the 
leaf; but the whole blade often curls inwards, converting 
the leaf into a temporary stomach. 
There can hardly be a doubt that all the plants belonging 
to these six genera have the power of dissolving animal 
matter by the aid of their secretion, which contains an acid, 
together with a ferment almost identical in nature with 
pepsin; and that they afterwards absorb the matter thus 
digested. This is certainly the case with Drosera, Droso- 
phyllum, and Dionea; almost certainly with Aldrovanda ; 
and, from analogy, very probable with Roridula and Byblis. 
We can thus understand how it is that the three first-named 
2,568,099 glandular hairs. The hairs 
were counted late in the autumn, and 
by the following spring (May) the 
leaves of some other plants of the 
same lot were found to be from one- 
third to one-fourth broader and 
longer than they were before; so 
that no doubt the glandular hairs 
had increased in number, and }ro- 
bably now much exceeded three 
millions. 
